System to control variable transmission windows having a security system interface

ABSTRACT

An electrical control system is disclosed for controlling a plurality of variable transmittance windows. The electrical control system of the present invention comprises a master control circuit for supplying control signals representing transmittance levels for the variable transmission windows, and a plurality of window control circuits coupled to each of the master control circuit. Because the window control circuits can sense abnormal load conditions in the variable transmission windows, the system further includes an interface to a security system to inform of a potential intrusion. Each window control circuit controls the transmittance of at least one of the variable transmission windows in response to control signals received from the master control circuit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.09/624,792, entitled “SYSTEM TO INTERCONNECT, LINK, AND CONTROL VARIABLETRANSMISSION WINDOWS AND VARIABLE TRANSMISSION WINDOW CONSTRUCTIONS,”filed on Jul. 25, 2000 by Jon H. Bechtel et al., now U.S. Pat. No.6,567,708, the entire disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention generally relates to variable transmissionwindows. More specifically, the present invention relates to controlsystems for controlling the transmission of variable transmissionwindows and to various constructions of variable transmission windows.

Variable transmittance light filters, such as electrochromic lightfilters, have been proposed for use in architectural windows, skylights,and in windows and sunroofs for automobiles. Such variable transmittancelight filters reduce the transmittance of direct or reflected sun lightduring daytime through the window, while not reducing such transmittanceduring nighttime. Not only do such light filters reduce bothersome glareand ambient brightness, but they also reduce fading and generated heatcaused by the transmission of sunlight through the window.

Variable transmission windows have not been widely accepted commerciallyfor several reasons. First, they tend to be very expensive due to thecost of materials required for their construction, and their complexconstruction makes mass-production difficult. Additionally,electrochromic windows tend to have a lower life expectancy thanconventional windows due to degradation of the electrochromic materialsused in the windows. The combination of added cost and lower lifeexpectancy have deterred many architects and builders from usingelectrochromic windows.

Recent advances have resulted in electrochromic windows that cost lessand have higher life expectancies. Examples of such electrochromicwindows are disclosed in commonly assigned U.S. Pat. No. 6,407,847,entitled “ELECTROCHROMIC WINDOWS AND METHOD OF MANUFACTURING THE SAME.”Perhaps because electrochromic windows had not previously been widelyaccepted commercially, little thought had been given to practical windowconstructions that enable power to be delivered to an electrochromicwindow element through conventional types of window frame assemblies.While electrochromic windows have been discussed in the prior art, thetypical construction that is disclosed merely shows two or more wiresextending from a window frame in which the electrochromic windowelements are mounted. Such a construction does not allow forelectrochromic window elements to be mounted in a window sash that movesrelative to a stationary window frame, nor do such constructions allowfor easy construction of such window assemblies or easy replacement ofan electrochromic window element. In addition, electrochromic windowassemblies can be relatively heavy, as may some conventional windowassemblies. Thus, if the window installers must additionally handledangling wires from a window assembly when attempting to install theheavy window assembly in a building, an additional person may berequired just to manage the wires as the windows are being installed.Further, once the wires are secured to a power source, replacement ofthe windows is more difficult.

The prior art also fails to address techniques for controlling thetransmission of a plurality of such electrochromic windows in a buildingeither independently or in various groupings. Therefore, there exists aneed for an electrical control system for controlling the transmittanceof a plurality of variable transmission windows in a building.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide anelectrical control system for controlling a plurality of variabletransmittance windows. To achieve these and other aspects andadvantages, the electrical control system of the present inventioncomprises a master control circuit for supplying control signalsrepresenting transmittance levels for the variable transmission windows,and a plurality of window control circuits coupled to each of the mastercontrol circuits. Each window control circuit controls the transmittanceof at least one of the variable transmission windows in response tocontrol signals received from the master control circuit.

Another aspect of the present invention is to provide a buildingcomprising a plurality of variable transmission windows, a mastercontrol circuit for supplying control signals representing transmittancelevels for the variable transmission windows, and a plurality of windowcontrol circuits coupled to the master control circuit. Each windowcontrol circuit controlling the transmittance of at least one of thevariable transmission windows in response to control signals receivedfrom the master control circuit.

An additional aspect of the present invention is to provide a windowcontrol circuit for controlling at least one variable transmissionwindow in response to signals received from a master control circuit.The window control circuit of the present invention comprises a microcontroller coupled to receive the signals from the master controlcircuit, and a switching regulator circuit for supplying power to the atleast one variable transmission window. The switching regulator circuitis coupled to the micro controller and is responsive to signals receivedfrom the micro controller to selectively vary the power supplied to thevariable transmission window.

Another aspect of the present invention is to provide a master controlcircuit for supplying control signals to at least one window controlcircuit that controls the transmittance of at least one variabletransmission window in response to the control signals. The mastercontrol circuit of the present invention comprises a micro controllerfor generating signals representing a desired transmittance for thevariable transmission window and a power switching circuit for supplyingpower to the at least one window control circuit. The power switchingcircuit is coupled to the micro controller and is responsive to signalsreceived from the micro controller to vary the power supplied to the atleast one window control circuit.

An additional aspect of the invention is to provide an electricalcontrol system for controlling the transmittance of at least onevariable transmission window. The control system of the presentinvention comprises a control circuit coupled to the variabletransmission window for selectively varying the electrical energyapplied to the variable transmission window, and a receiver forreceiving a command from a remote control device via a wirelesscommunication link. The receiver is coupled to the control circuit tosupply a control signal representing the received command. The controlcircuit responds to the receipt of a control signal by varying thetransmittance of the variable transmission window.

Another aspect of the present invention is to provide an electricalcontrol system for controlling the transmittance of at least onevariable transmission window. The control system of the presentinvention comprises a control circuit coupled to the variabletransmission window for selectively varying the electrical energyapplied to the variable transmission window, a sensing circuit forsensing an abnormal electrical load condition including a near short ornear open circuit, in the variable transmission window, and a securitysystem interface coupled to receive an indication from the sensingcircuit that an abnormal electrical condition exists in the variabletransmission window.

Another aspect of the present invention pertains to a method ofdetermining whether a security breach has occurred through the breakageor opening of a variable transmission window, the variable transmissionwindow providing a current path when closed. The inventive methodcomprises the steps of sensing whether there is an electrical near shortor near open circuit or other abnormal electrical performance indicativeof physical damage to the window in the current path through thevariable transmission window, and determining that there has been asecurity breach through the variable transmission window when anelectrical near short or near open circuit or other abnormal conditionis sensed.

An additional aspect of the present invention is to provide a windowhaving a transmittance that varies in response to an electrical signalwhere the window comprises a window frame; a sash mounted to the windowframe so as to be movable relative to the window frame; a variabletransmission window element mounted in the sash; a first electricalcoupler mounted to the window frame and electrically coupled to a sourceof an electrical signal; and a second electrical coupler mounted to thesash and electrically coupled to the variable transmission windowelement, the second electrical coupler moves relative to the firstelectrical coupler and contacts the first electrical coupler to therebyenable the electrical signal to be transmitted from the window frame tothe variable transmission window element.

Another aspect of the present invention is to provide a window having atransmittance that varies in response to an electrical signal where thewindow comprises a window frame assembly; a variable transmission windowelement mounted in the window frame assembly; a first electrical couplermounted to the window frame assembly and electrically coupled to asource of an electrical signal; and a second electrical coupler mountedto the variable transmission window element. The first electricalcoupler includes a resilient contact member biased towards the secondelectrical coupler.

Yet another aspect of the present invention is to provide a windowhaving a transmittance that varies in response to an electrical signal,where the window comprises: a window frame; a sash mounted to the windowframe so as to be movable relative to the window frame; a variabletransmission window element mounted in the sash; a first electricalcoupler mounted to the window frame and electrically coupled to a sourceof an electrical signal; a second electrical coupler mounted to the sashand electrically coupled to the variable transmission window element;and a flexible cable coupled between the first and second electricalcouplers to thereby enable the electrical signal to be transmitted fromthe window frame to the variable transmission window element, theflexible cable having a length sufficient to permit movement of the sashbetween open and closed positions.

Still another aspect of the present invention is to provide a windowhaving a transmittance that varies in response to an electrical signalwhere the window comprises: a window frame; a variable transmissionwindow element; a first electrical coupler mounted to the window frameand electrically coupled to a source of an electrical signal; and asecond electrical coupler electrically coupled to the variabletransmission window element. The first and second electrical couplershave contact surfaces that engage one another to thereby enable theelectrical signal to be transmitted from the window frame to thevariable transmission window element.

These and other features, advantages and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims and appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a block diagram of the electrical control system of thepresent invention;

FIG. 2A is a block diagram of a master control unit used in theelectrical control system shown in FIG. 1;

FIG. 2B is an electrical circuit diagram in block and schematic formshowing the details of an exemplary master control unit that may be usedto implement the master control unit shown in FIG. 2A;

FIG. 3A is a block diagram of a window control unit used in theelectrical control system shown in FIG. 1;

FIG. 3B is an electrical circuit diagram in block and schematic formillustrating an exemplary detailed construction of a window control unitthat may be used to implement the window control unit shown in FIG. 3A;

FIG. 4A shows an exemplary signal wave form as would be transmittedbetween a master control unit and the window control units of theelectrical system shown in FIG. 1;

FIG. 4B shows an exemplary idle wave form as would be transmittedbetween a master control unit and the window control units of theelectrical circuit shown in FIG. 1;

FIG. 4C shows the components of an instruction signal sent from a mastercontrol unit to the window control units with no data;

FIG. 4D shows the components of an instruction signal sent from a mastercontrol unit to the window control units with data write;

FIG. 4E shows the components of an instruction signal from a master unitto the window control units with data read;

FIG. 5A is a cross-sectional view of an electrical connector utilized ina window construction according to a first embodiment of the presentinvention;

FIG. 5B is a partial cross-sectional view of a modified portion of theconstruction shown in FIG. 5A;

FIG. 5C is an isometric view shown in partial cross section illustratinga non-opening window construction utilizing the electrical connectionshown in FIG. 5A;

FIG. 5D is an isometric view of the back of an electronic module thatmay be attached to the window frame shown in FIG. 5C;

FIG. 5E is an isometric view of the front of the electronic module shownin FIG. 5D;

FIG. 6 is an isometric view shown in partial cross section illustratinga casement window construction utilizing the electrical connection shownin FIG. 5A;

FIG. 7 is a cross-sectional view of an electrical connection for awindow construction according to a second embodiment of the presentinvention;

FIG. 8A is an isometric view in partial cross section showing theelectrical connection for a window construction according to a thirdembodiment of the present invention;

FIG. 8B is an elevational side view showing the electrical connectionportion for the window construction according to the third embodiment ofthe present invention;

FIG. 9 is an exploded isometric view of an electrical plug used in aconnection for a window construction according to a fourth embodiment ofthe present invention; and

FIG. 10 is a cross-sectional view of the electrical connection used inthe window construction according to the fourth embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numeralswill be used throughout the drawings to refer to the same or like parts.

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” “top,” “bottom,” andderivatives thereof shall relate to the invention as shown in thedrawings. However, it is to be understood that the invention may assumevarious alternative orientations, except where expressly specified tothe contrary. It is also to be understood that the specific deviceillustrated in the attached drawings and described in the followingspecification is simply an exemplary embodiment of the inventiveconcepts defined in the appended claims. Hence, specific dimensions,proportions, and other physical characteristics relating to theembodiment disclosed herein are not to be considered as limiting, unlessthe claims expressly state otherwise.

The present invention pertains to a novel electrical control system forcontrolling the transmission of a plurality of variable transmissionwindows and also pertains to various window constructions and variousconstructions of electrical connectors in those window constructionsthat make it practical to employ the electrical control system of thepresent invention. Other inventive aspects flowing from the combinedelectrical and mechanical structures described herein will becomeapparent to those skilled in the art and include, among other aspects, amethod for determining whether a security breach has occurred throughthe breakage or opening of a variable transmission window.

FIG. 1 shows a block diagram of the electrical system 900 of the presentinvention, which interconnects, links, and controls variabletransmission windows 44 a-44 b. A master unit 1000 (also referred toherein as a “master control circuit”) is connected to a power source1050, which is preferably attached to the AC power line. Master unit1000 is also coupled to one or more devices to receive and/or displayinformation. These devices may include one or more in combination of adisplay 103, a keypad 102, an interface 118 a to an external computer117 a, and/or a remote control interface 118 b and an associatedportable remote control input and/or output device 117 b. Master unit1000 may also optionally be coupled to an interface 118 c to a securityand/or fire or smoke detection system 117 c and in some cases mayincorporate these features directly. Master unit 1000 may also becoupled to temperature 83 and/or light sensors 80 to input data for usein performing control functions.

Power source 1050 may include a battery backup and is preferably but notnecessarily incorporated directly as part of master unit 1000. If powersource 1050 is equipped with battery backup and particularly if firealarm and/or security functions are included, it is preferred tocommunicate via an input to the micro controller 81 (FIG. 2A) in masterunit 1000 that power source 1050 is in battery backup mode and tocurtail certain energy consuming dimming functions and the like whichwill significantly extend battery life and not interfere with thecritical safety functions.

In larger systems, master unit 1000 may support more than onecommunication and energy supply path. In the simplest case, the circuitof FIGS. 2A and 2B, which supplies power to, and interfaces with, lines1004 and 1005, may be replicated and micro controller software supportmay be added for the multiple controller interface buses. More than onemaster unit may also be linked in a system either by providing aninterface to link directly with another master unit or by interfacingmultiple units to another external computer or control system.

Master unit 1000 communicates with window control units 1100 a-1100 b(also referred to herein as “window control circuits”) that are providedfor individual variable transmission windows or clusters of windows 44a-44 b. Window control units 1100 a-1100 b may include window closuredetection functions 1130 a-1130 b for use in associated or integratedsecurity systems 117 c. Window control units 1100 a-1100 b may alsoinclude abnormal window detection functions 1132 a-1132 b by which theymonitor things such as supply current to window 44 a-44 b under specificdrive conditions to detect abnormal response of the window. Abnormalresponses, such as a near short or near open, would likely result fromwindow breakage due to forced entry and as such provides a useful inputto a security system 117 c. In a number of embodiments, contact tovariable transmission window 44 a-44 b is broken when the window isopen. In these cases, a complete open circuit to the variabletransmission window indicates that it is open. This may also be used forsecurity purposes. Master unit 1000 may also communicate with separatedevices 1200 provided for displaying information to, and inputtingcontrol commands from, users and/or intrusion and/or smoke and firedetection functions. Optionally, features of the devices above may becombined or separated and regrouped in almost any combination asinterface 51 a-51 c and/or window control units. Any of the units mayinput other data used to control the system such as temperatures orlight levels, and any of the units may include a remote controlinterface and associated portable remote control input or two-wayinput/output device 53 a-53 c. Any of the units may also have their owndisplay 47 a-47 c and/or input device such as a touch panel or keypad 46a-46 c. The communication between units may take any one of a number offorms including those incorporating ethernet links or data links ingeneral purpose control and data transmission systems for homes orcommercial buildings. Furthermore, these links may include RF or opticalpaths which may either be through air or via fiber. A preferredconfiguration incorporates a particularly inexpensive two-wireinterconnect arrangement or interface bus by which master unit 1000energizes and communicates with all or a group of the window controlunit(s) 100 a-1100 b and remote interface unit(s) 1200 over a singlepair 1004 and 1005 of low voltage wires. The operating voltage overwires 1004 and 1005 is preferably toward the higher end of that which ispermissible and safe for a low voltage system so that appreciable powerat an acceptable current may be supplied to a large number of units witha minimal number of separate interface buses in a large installation.

The system described bears some general resemblance to two wire smokedetector systems used in some commercial installations, but has manynovel features which in addition to the very different application orthe new shared application, distinguish it from these systems.

FIG. 2A depicts a combined circuit and block diagram of a preferreddesign for master unit 1000 of FIG. 1. As shown in FIG. 2A, master unit1000 includes a power source 1050 having two or more terminals 60 and 61for connection to a 120 VAC commercial power line. As explained furtherbelow, power source 1050 provides a common ground 79 and a 30 voltoutput on line 128. Master unit 1000 also includes a voltage converter1010 that is coupled to line 128 to convert the 30 volt power on line128 to a 5 volt output that is supplied to the various circuitcomponents of master unit 1000. Master unit 1000 further includes amicro controller 81, a power switch circuit 1012, a current limitingcircuit 1014, a current mirror circuit 1016, a current sink circuit1018, a pull-up circuit 1020, and a data extraction circuit 1022. Thedetailed operation and construction of these components is describedfurther below with reference to FIG. 2B.

As shown in FIG. 2B, power source 1050 includes a transformer 62 havingcenter-tapped secondary coils 129, rectifier diodes 63 and 64, and acapacitor 65. Transformer 62 receives power to its primary from the ACline via terminals 60 and 61. The isolated, center-tapped secondary 129supplies a DC voltage of, for example, 30 volts to line 128 throughrectifier diodes 63 and 64. Capacitor 65 filters this supply and limitstransient voltages. Additional surge protection, not shown, is desirableand may be included.

Voltage converter 1106 may include a current limiting resistor 110, avoltage-clamping zener diode 74, and a filter capacitor 75. Current fromsupply line 128 flows through current limiting resistor 110 tovoltage-clamping zener diode 74 and filter capacitor 75 to supply microcontroller 81 with a supply voltage of, for example, 5 volts on line104. Standard circuits such as resonators or power on reset circuitconnections, which differ widely from one micro controller to anotherbut which are fully described in application circuits for each, are notshown here or in the circuit of FIGS. 2B and 3B.

Each micro controller 81 (and 14, FIGS. 3A and 3B) in the system isprovided with either an integrated or separate re-writeable memory whichwill not lose stored data when power is lost. Common types now includeflash memories and EE (electronically erasable memories). Thesememories, especially in the slave window control units, do not need tobe large but among other things are required to store unit addresses andother configuration and preference data. The black square terminal 76connected to micro controller power supply line 104 is connected to theother similar appearing terminals in the circuit. Likewise, the groundsymbols are all interconnected with ground terminal 79 which isconnected to terminal 101.

Power switching circuit 1012 may include a limiting resistor 91 coupledto an output 123 of micro controller 81, a level shifting transistor 90,a p-channel FET 89, a resistor 88, and a zener diode 87. Output 123 ofmicro controller 81 is switched low at a rate and duty cycle of, forexample, 1 kHz and 50 percent. When output 123 is pulled low, currentthrough limiting resistor 91 and level shifting transistor 90 pulls thegate of p-channel FET 89 low turning it on. This in turn pulls line 124close to the positive supply potential on line 128 and supplies acharging pulse to the internal circuit components through a diode 67 andto external units connected in parallel to terminal 95. The balancebetween the gate capacitance of FET 89 and the resistance of resistor 91limits the rate of rise of the turn on voltage and the resulting slewrate of turn on of FET 89 to limit radiated interference. When output123 is switched high, current is no longer drawn through transistor 90,and resistor 88 discharges the gate capacitor of FET 89 at a limitedrate to limit the turnoff rate of FET 89. Zener diode 87 limits gatevoltage to FET 89 to a safe level.

Current limiting circuit 1014 includes a current sensing resistor 85, atransistor 84, and a resistor 86. The voltage on current sensingresistor 85 turns on transistor 84 when the current is excessive to turnoff FET 89 and limit short circuit current.

Current mirror 1016 includes transistors 93 and 94, resistors 92, 99,and 100, and a filter capacitor 98. Current mirror 1016 creates afiltered voltage at an input port 105 of micro controller 81, which islevel shifted from, and tracks, preferably at an amplified level, thevoltage on current sensing resistor 85. Port 105 is an analog port tomicro controller 81. Micro controller 81 samples the voltage on port105, which is indicative of the current supplied to the connected unitsfor a number of purposes, two of which are: First, when the sensedcurrent is very high indicating a short, turn on of FET 89 is inhibitedso that the analog current limiting components are not overloaded. Athigh currents that are still in a normal operating range, microcontroller 81 may be programmed to delay or reduce darkening of some ofwindows 44 a and 44 b to lower the peak current requirement therebyperforming a form of load demand leveling.

As described above, the supply current is supplied in pulses. Thesepulses serve as a time base for communication which takes place duringthe off periods in the pulsed supply. There are three components used bymaster unit 1000 to communicate with other units on lines 1004 and 1005.First, a current sink 1018 composed of transistors 113 and 114 andresistors 112, 96, and 115 is turned on to pull line 124 and theterminals of other units connected to output terminal 95 low during theoff periods of the supply cycle. Master unit 1000 and each of theconnected units 1110 a, 1110 b, and 1200 has a pull-up circuit 1020 and1108, respectively, to supply enough current from the positive supply tooverride current sink 1018 and pull line 124 high for the communicationarrangement which will be described below. Output 122 of microcontroller 81 is switched high to turn on current sink 1018.

Pull-up circuit 1020 may include a current limiting resistor 78, a levelshifting transistor 77, a current limiting resistor 69, a transistor 68,a diode 67, a filter capacitor 73, and a resistor 111. To pull line 124high, micro controller 81 switches output 120 low, which is coupled topull-up circuit 1020, thereby drawing current through current limitingresistor 78 and level shifting transistor 77 turning on transistor 68thereby pulling line 124 and associated output terminal 95 high throughcurrent limiting resistor 69. Diode 67 charges filter capacitor 73during the half cycle charging cycle to provide the positive supply atline 126 for pull-up circuit 1020.

Data extraction circuit 1022 may include resistors 72 and 109, atransistor 71, and a current limiting resistor 70. When the voltage online 124 significantly exceeds the micro controller supply voltage online 104, current through current limiting resistor 70 turns ontransistor 71 pulling input terminal 119 of micro controller 81 high.Micro controller 81 samples the voltage at terminal 119 to detect thelogic level on line 124. Resistor 109 limits input current at inputterminal 119 and resistor 72 pulls the input low when line 124 is at thelogic low level.

Master unit 1000 may further include a MOV 130 and a diode 66. MOV 130limits transient voltages on line 124. For units designed for a largenumber of interconnecting devices, an alternative voltage overprotectiondevice, which has lower capacitance, may be preferred. Diode 66 limitsreverse voltage transients on line 124.

Input device 102, preferably a small keypad, is connected to microcontroller 81 by lines in a bus 106 and similarly, display 103, which ispreferably an LCD or vacuum fluorescent display, is connected to microcontroller 81 through a bus 107. A thermistor 83 forms a voltage dividerwith a series resistor 82 such that the temperature dependent voltagemay be read at an analog input 130 of micro controller 81. Light sensor80 is preferably an active pixel type described in commonly-assignedU.S. Pat. No. 6,313,457, entitled “MOISTURE DETECTING SYSTEM USINGSEMICONDUCTOR LIGHT SENSOR WITH INTEGRAL CHARGE COLLECTION,” filed onApr. 13, 1999, and is controlled and read through a bi-directional port131 of micro controller 81. The entire disclosure of U.S. Pat. No.6,313,457 is incorporated herein by reference.

Interface unit 118 is any of a number of optional interface units asdescribed above connected to micro controller 81 by a bus 127. Externalunit 117 communicates with interface unit 118 over path 125, which isoptionally and preferably bi-directional. Additional components similarto 117 and 118 may be added to interface to a multiplicity of externalsystems 117 a and 117 b and security and/or fire detection systems 117 cmay be the target system 117 for versions incorporating an interfaceeither to single or to multiple external systems.

FIGS. 3A and 3B are combined schematic and block diagrams of a preferredcircuit design for the slave units depicted in blocks 1100 a, 1100 b,and 1200 of FIG. 1. As shown in FIG. 3A, window control unit 1100includes a micro controller 14, a power source 1104 for supplying poweron line 58, a voltage converter 1106 for supplying 5 volt power for thevarious circuit components, a pull-up circuit 1108, a data extractioncircuit 1110, a current limiting circuit 1112, a switching regulatorcircuit 1114, a shorting circuit 1116, a filter 1118, an over-voltageprotection circuit 1120, and a pair of terminals 43 and 45 for couplingto one or more variable transmission window elements 44. Unit 1100 mayfurther include an inductor 37, a current monitoring resistor 561, and aSchottky barrier diode 38. The detailed functions of these componentsand exemplary circuit constructions are shown and described with respectto FIG. 3B below. Remote interface unit 1200 would have a similarconstruction to window control units 1100, but need not have thecomponents for controlling the transmittance of a window. Remoteinterface unit 1200 may also be configured to perform intrusiondetection functions 1202 and smoke detection functions 1204.

Circuits for the various optional functions may be added, replicated, oromitted depending on whether the particular function is present,duplicated, or not present in the particular unit. The function of microcontroller 14 is quite different from that of master unit 1000 of FIG.1, but the circuit configuration is very similar and a micro controller14, which is similar but perhaps smaller in size than the microcontroller 81 of FIGS. 2A and 2B, is preferably used.

The unit receives pulsed power on terminal 1. When multiple units areconnected in parallel, terminal 1 is connected in parallel to thecorresponding terminals of the similar units and to terminal 95 ofmaster unit 1000 in FIG. 2A. A ground terminal 2 is connected to thecorresponding ground terminals of similar parallel connected units andto ground terminal 101 of master unit 1000 in FIG. 2A. These twoparallel interconnecting lines correspond to lines 1004 and 1005 of FIG.1.

Each unit may also include a MOV 3 and a diode 5 coupled acrossterminals 1 and 2. MOV 3 serves the same function as MOV 130 in FIG. 2Band the same preference for an alternative lower capacitance device forapplications where a large number of devices are to be connected inparallel applies.

Power source 1104 includes a diode 4 and a filter capacitor 36. Thepulsed power from terminal 95 of the master unit in FIG. 2A flowsthrough diode 4 and charges filter capacitor 36 to provide supplyvoltage 58.

Pull-up circuit 1108 includes resistors 7, 11, and 13 and transistors 6and 12, and is responsive to a signaling output supplied by microcontroller 14 at output terminal 55. Transistor 6 is turned on to pullline 560 and terminal 1 high to communicate back to the master unit inthe signaling scheme to be described in connection with FIG. 4. Dataextraction circuit 1110 may include resistors 8, 10, and 48 and atransistor 9. Data extraction circuit 1110 is coupled to line 560 andextracts data signals received at terminal 1 and supplies the data tomicro controller 14 at input terminal 54. The signaling output atterminal 55 of micro controller 14 and the signaling input at terminal54 and the function of the associated level shifting circuits aresimilar to the nearly identical functions in FIG. 2B so a descriptionwill not be repeated. Likewise, the optional input device 46, theoptional display 47, thermistor 26, and light sensor 22 are similar tocorresponding circuits in FIGS. 2A and 2B.

Current monitoring resistor 561 is in series with the window supply,which is provided by switching regulator circuit 1114 and window 44. Abreak in window 44 is very likely to cause a partial short or partialopen or other abnormal loading condition indicative of damage to window44, in the electrical circuit and in either case causes an abnormalcurrent level for a given drive condition.

Input terminal 33 of micro controller 14, as described elsewhere,receives an analog input by which micro controller 14 measures thevoltage supplied to window 44. Input 562 is a similar analog input. Thetwo inputs in combination enable micro controller 14 to measure voltageon each side of resistor 561 and to take the difference to determine theresulting voltage drop across resistor 561 and thereby to calculate thecurrent supplied to window 44. Measurements of the voltages at inputs 33and 562 are preferably taken in very quick succession and at a knowntime in the pulsing cycle of the switching power supply to obtainconsistent readings. As another alternative or as an additionalmeasurement, the voltage decay rate of window 44 when it is opencircuited may be measured and compared with a recent result to determinea sudden change due to breakage of window 44.

During maintenance of the window element in a steady, reducedtransmission mode, the control module measures and records the readingsof supply current to the variable transmission window elements andcompares them against corresponding recently recorded readings to detectabrupt, abnormally large changes in supply current which nearly alwaysindicate window breakage or loss of connection. The window control unitmay apply short interruptions of predetermined duration in the supplycurrent to the variable transmission element. The voltage decaycharacteristic due to the interruptions in the supply current may alsobe measured, recorded and compared against values obtained from likemeasurements which were recently recorded. Again, abrupt, abnormallylarge changes normally indicate window breakage or loss of connection.

When the window is clear, the control module periodically supplies avoltage pulse of known amplitude and duration to the variabletransmission element and monitors and records the amplitude and waveformof the responding supply current to the variable transmission element.Normally a current amplitude and decay characteristic such as decay timeconstant are recorded. The voltage amplitude and voltage decay waveformof the variable transmission element after termination of the pulse mayalso be recorded. The response measurements are compared withcorresponding recent response measurements to detect abrupt, abnormallylarge changes in the corresponding response readings which normallyindicate window breakage or loss of connection.

When monitoring for security is enabled, the master unit normally pollseach of the window control units to signal changes which indicate aprobable breach of security. The abnormal conditions noted above aresignaled or reported in response to the query from the master unit aftersuch conditions are detected.

In a startup sequence after the system is installed or after units areadded or replaced, individual slave units 1100/1200 must be identifiedso that addresses may be assigned by master unit 1000. The preferredsequence to do this is to place master unit 1000 in a special startupaddress assignment mode. Master unit 1000 may in sequence broadcast thenext new address and then issue a query instruction to see if a slavehas accepted this address and responded. In order to limit more than oneslave unit 1100/1200 from accepting the same address and also to aid inestablishing an identity between addresses and specific units, it ispreferred that, while in the address assignment mode, the installeractuate or optionally toggle an input device 46 for each unit for whichan address is to be assigned one at a time in sequence and that only theslave unit for which the input is actuated or toggled may accept theaddress. When a display 47 is provided, it is preferable to have display47 respond to verify that the address assignment has been made and thatthe unit is functioning. Individually exercising inputs 46 of the unitto receive the next address assignment prevents contention over havingmultiple units accept the same address and collide on the bus in tryingto answer back at the same time and, as noted before, provides aframework in which specific addresses may be correlated with specificunits. As will be noted later, it is often preferable to have the windowcontrol module hidden by recessing it in the window sash and a separatemodule for the user interface for the control is often preferable. Insuch cases, the window control module may not require or have an inputdevice 46 for normal user interface. Since an input is required or atleast preferred for address assignment, input device 46 may, in thiscase, be a magnetically actuated reed switch or hall effect sensor orother magnetic field strength sensor which may be actuated by bringing amagnet in close proximity to the window control module. For moduleswhich do not have a sophisticated display, it is preferred to have atleast one or two indicator LEDs to, for example, serve as display 47 andindicate status in address assignment or troubleshooting procedures andto indicate working status during normal operation. In windows whichopen, the same reed switch or other field strength sensor may beactuated by a magnet in an adjoining window sash or latch mechanism insuch a way that the switch is actuated only when the window is properlyclosed. Note that this function is similar to that supplied by separatewires, magnets and reed switches in security systems common today; but,in this case, everything except the embedded permanent magnet is alreadypart of the window control system. The window closure status may berelayed to security system 117 c or, in some cases, the security andeven fire detection functions may be incorporated as part of the windowcontrol system. Note that there are many reasons to identify each modulein the system. Two of the reasons follow: first, a control input modulemust be associated with the window controller of the window beingcontrolled. Second, in more elaborate systems, status or alarm displaysmay indicate the status information on various specific units in thesystem either in text or graphic form requiring knowledge of unitlocation.

In a typical application, each remote control 53 may be used by theoccupant of an individual office to control or to override the automaticcontrol of the window dimming in his or her office. For suchapplications, there is not a great need for interface 51 to be capableof sending information to remote unit 53 and the individual remotecontrols 53 for each office may be for input of commands to the systemonly. For such an application, it is also preferable to use infraredbased controls which are inexpensive and very good for short range.Furthermore, infrared signals will not travel through a wall tointerfere with a similar unit in an adjoining office. In manyapplications of such systems, the receiver and controller do not need tobe keyed together since the rooms in which they are used provideadequate separation. Having remote unit 53 work with receiver 51 indifferent locations may be beneficial. In the circuit of FIGS. 3A and3B, interface 51 receives infrared signals 59 from remote unit 53 andcommunicates with micro controller 14 over a bus 52.

Voltage converter 1106 may include a zener diode 17, a capacitor 18, anda resistor 16. Current limiting circuit 1112 may include a transistor 27and resistors 29 and 30. Switching regulator 1114 may include a resistor20 coupled to an output port 56 of micro controller 14, a resistor 49, atransistor 32, a zener diode 28, an inductor 37, a diode 38, and ap-channel FET 31. P-channel FET 31 is interfaced in a way which isalmost identical to that for FET 89, which is part of the pulsed powersupply switch 1012 shown in FIG. 2B. However, FET 31 has a verydifferent application and serves as part of switching regulator 1112 toprovide a variable voltage supply to window element or elements 44.

Unit 1100 preferably includes an over-voltage protection circuit 1120coupled between the window power supply line and ground line 15. Anexemplary over-voltage protection circuit is shown in FIG. 3B asincluding diodes 41 and 42 coupled in series. Series diodes 41 and 42conduct to protect the variable transmission window 44 from serious overvoltage in the event of a circuit malfunction. Unit 1100 may alsoinclude a capacitor 40, which is relatively low in value and serves as afilter 1118 to filter the output of switching regulator 1114.

Micro controller 14 pulls output terminal 56 low to turn on FET 31 andthe values of resistors 20 and 49 are chosen as in the similar circuitin FIG. 2B to limit turn on and turn off times of switching regulator1114 to achieve the desired balance between excessive switching lossesand excessive radiated interference. The micro controller program isdesigned to provide a controlled, variable, and relatively short on timeduty cycle for output transistor 31. The output voltage is normally inthe range of about 1 volt which is approximately one-thirtieth of thenominal supply voltage at line 58 and the output voltage to the windowis approximately equal to the supply voltage multiplied by the dutycycle of the signal output at terminal 56. The voltage applied to thewindow is frequently measured at analog input terminal 33 of microcontroller 14. When the voltage is higher than desired, the on time dutycycle of FET 31 is reduced and when the voltage is lower than desired,the on time duty cycle is increased by micro controller 14. When it isdesired to clear window 44, micro controller 14 switches output terminal56 high to turn off FET 31 and switches output terminal 57 high to turnon a shorting transistor 39 which speeds clearing of the window.Shorting transistor 39 and a resistor 21 together form shorting circuit1116. Inductor 37 tends to maintain a steady supply current to thewindow 44 during the switching cycle and Schottky barrier diode 38carries current when FET 31 is in the off portion of the cycle.

Micro controller 14 and/or micro controller 81 may be programmed toprotect the window elements from segregation problems that result whenthe window elements are otherwise left in their low transmission statesfor an extended period of time. More specifically, the micro controllersmay be programmed to bring the associated window elements to their hightransmission states for a predetermined period of time (i.e., one to twohours) at specified times (i.e., at night) so as to ensure that thewindows are not continuously left in their low transmission states forextended periods of time.

Many alternative signaling protocols may be used, but the one chosen forthe preferred embodiment provides multiplexing of power transmission andsignaling for a number of window control units 1100 and remote interfaceunits 1200 on one pair of low voltage wires 1004 and 1005 and providesfor electrical interfaces to the modules which are of minimal cost. Inthe preferred arrangement, master unit 1000 is always the master and theother units are always slaves, but in alternate arrangements still inthe scope of this invention, this is not mandatory. Master unit 1000initiates all transmission and polls slave units 1100/1200 to receivedata inputs. When an input sequence from a remote user interface unit1200 is in progress, master unit 1000 increases the polling rate so thatthe overall response rate of the system is acceptable. All data unittransmissions are 9 bits long with a “1” start bit always beginning thetransmission and with 8 data bits which immediately follow the startbit. A tenth odd parity bit may optionally be added. Master unit 1000always precedes a transmission with an idle period of at least 9 bitsand once started, the transmission is uninterrupted with every bitperiod used so that there will be a “1” at least every 9th bit duringthe transmission sequence. In this way, the start of a transmissionsequence is always discernable by looking for the first “1” bit after atleast 9 consecutive zero bits which signify an idle period. Such a bitis the start bit for the next transmission. Master unit 1000 starts thetransmission sequence with transmission of the address of the slave unitwhich is to respond or in a few cases with a general group broadcastaddress to which some or all of the units respond. The secondtransmission in the sequence is always an instruction and, whererequired, this is followed by one or more words of data written bymaster unit 1000 and received by the addressed slave unit for a writeinstruction or one or more data words transmitted by the addressed slaveunit to master unit 1000 as a result of a read instruction from masterunit 1000.

A typical signal waveform which would appear between lines 1004 and 1005of FIG. 1 for transmission of binary “01100101” is depicted in FIG. 4A.The highest signal voltages (nominally 30V) occur during the half wavepower supply pulse output portions of the cycle labeled with a “p.”These power output pulses serve to establish the timing for the datatransmission, one bit being transmitted between each power pulse in thesignaling half cycles labeled with an “s.” During the signaling portionsof the waveform, master unit 1000 pulls the line low with a currentsink. To send a “0,” master unit 1000 or a responding slave unit takesno action during the bit period, and to send a “1,” master unit 1000 ora responding slave unit waits until it detects a logic low after thepower pulse and pulls the line high during the remainder of the bitperiod into the start of the next power pulse. Thus, the falling edgesof the power pulses are left intact for timing purposes. As a practicalmatter, each unit should wait a short time after detecting the fallingedge of the power pulse before pulling the line high so as to allow thepulse to remain low for approximately one-third of the signaling portionof the waveform period (i.e., about one-sixth of the total bit period)so that other units on the line have time to detect the negative edge ofthe power pulse. In the example circuit with appropriate choice ofresistance values, the logic threshold between the “0” and “1” states ofthe two wire transmission line may be about 6 volts. A “1” bittransmission labeled with “Start” is always sent immediately before thetransmission of each packet of eight data bits so that the start of thetransmission sequence is unambiguous and so that there will be a “1” atleast every ninth bit during a data transmission.

The “Idle waveform:” is shown in FIG. 4B and may have more than, but notless than, nine consecutive “0” bits and must be the first part of anytransmission sequence initiated by master unit 1000. Once thetransmission is started, no bit gaps are allowed since these couldresult in more than eight consecutive “0” bits which would confuseslaves listening for their address or a broadcast address on the line.Examples of the byte order for “An instruction from the master with nodata:,” “An instruction from the master with data write:,” and “Aninstruction from the master data read:” are shown in FIGS. 4C, 4D, and4E, respectively. Instructions where data is read or written may containmultiple data bytes as long as no gaps occur in the transmission and aslong as they conform to a requirement on the maximum time that the busmay be tied up with any one transmission.

Terminals 43 and 45 of the circuit shown in FIG. 3A must each beconnected to variable transmission window 44. FIG. 5A shows across-sectional view of the details of a contact assembly 502 of awindow assembly 500 for making one of these two connections. Forpurposes of illustration, the connection of terminal 43 is describedbelow. It should be appreciated that the connection of terminal 45 wouldbe the same or similar to that of terminal 43.

As shown in FIG. 5A, window assembly 500 includes a sash 543 in which awindow unit 501 is mounted optionally, being removable for replacement.Window unit 501 may be sealed and secured within sash 543 using glazing532 in a manner well known in the art. Window unit 501 is preferably aninsulated window including a pair of spaced glass panes 533 and 542 anda variable transmission window element 541 positioned between inner pane542 and outer pane 533. Cement 540 or other supporting structures may beprovided between panes 533 and 542 to provide an airtight chamber inwhich an insulating gas such as Argon may be contained, and to maintainspacing and structure integrity of window unit 501. Variabletransmission window element 541 is preferably, but not necessarily,electrochromic and is shown as including a first conductive clip 536 anda second conductive clip 548 each secured to the edges of a respectiveone of a pair of transparent elements 504 and 506. A gold-plated contactpad 539 may also be provided at the edge of window unit 501 and isconnected to clip 536 by a connector wire 535. Another contact pad andwire (not shown) are used to provide a connection to clip 548. Windowunit 501 may optionally have any of the constructions, but is notlimited to these constructions, described in commonly-assigned U.S. Pat.No. 6,407,847, entitled “ELECTROCHROMIC WINDOWS AND METHOD OFMANUFACTURING THE SAME.” The entire disclosure of that patent isincorporated herein by reference.

As shown in FIG. 5A, terminal 43 is connected to a metal pad 528 and theillustrated contact assembly extends the connection to conductive clip536 in variable transmission window element 541. In detail, contactassembly 502 includes a probe assembly 525 having an insulating, plasticsleeve 527 and a metal sleeve 554, which is necked at end 553 to retaina plunger 526 and which also has a small flange so that it does notslide into the clearance hole in the end of plastic sleeve 527. Metalsleeve 554 is swaged to a smaller diameter at its opposite end to retaina ball 524. A helical compression spring 522 (the wires of which areshown in cross-sectioned view) creates a separating force and a reliableconducting path between plunger 526 and ball 524. This separating forceshould be at least several hundred grams. Plunger 526 has a head 555which is enlarged in diameter to provide a smooth sliding fit in metalsleeve 554 to retain plunger 526 from coming out of the necked end 553of metal sleeve 554. Head 555 has a conical top to center spring 522.

Contact assembly 502 further includes a plunger assembly 530 having asimilar construction as probe assembly 525. Plunger assembly 530includes a metal sleeve 521, which has a larger flange 537 that bearsagainst a plastic insulating flanged sleeve 538 and prevents metalsleeve 521 from sliding further into plastic sleeve 538. Plungerassembly 530 extends through a cross hole in plastic sleeve 527 of probeassembly 525. The cross hole prevents plunger assembly 530 from beingpushed away by side pressure exerted by ball 524 of probe assembly 525,which presses against it. Contact assembly 502 provides a reliablecontact path from pad 528 to plunger 526; to helical spring 522; to ball524; to metal sleeve 523; to the ball, helical spring, and plunger ofplunger assembly 530; to contact pad 539; to connecting wire 535; andfinally to contact clip 536 of variable transmission window element 541.Flange 552 may include an index notch 551, the position of which is usedto indicate proper rotational alignment of the sleeve 527 to insertplunger assembly 530 during the assembly process. Note that in theapplication, flange 552 of insulating sleeve 527 and the flange oninsulating sleeve 538 and the cylindrical surfaces of the sleeves andholes adjoining these flanges bear the necessary mechanical loads so thecontact assembly will work quite well in a hollow extruded aluminum orhollow plastic sash. Also, the contact is fully insulated from a metalsash.

A second, preferably identical, contact assembly makes contact to a padsimilar to pad 539 which is attached to contact clip 548. This assemblyis typically spaced, for example, about 1 inch away and would be visiblein another cross section through the window.

Each of the contacting members is preferably nickel plated with goldplating over the top. The helical springs are preferably of lowresistivity tempered beryllium copper alloy so that resistance throughthe length of the coil is small. The total resistance through thecontact path should preferably not exceed several tenths of an ohm. Thehelical spring and plunger assembly is chosen because for long termreliable operation, a relatively high contact force should bemaintained. Plunger 534 must travel a number of tenths of an inch tocover normal tolerances for the positioning of window unit 501 in sash543. Likewise, plunger 526 must travel a number of tenths of an inch toallow for tolerances in the closed position of the window. Furthermore,adequate contact force must be maintained over the plunger travelsexpected for this full tolerance range. The helical spring is one of themost efficient ways of utilizing a structural member to store elasticenergy. To keep size relatively small, stress levels low enough tominimize relaxation and fatigue, and contact forces high and uniform,the efficiencies of this near optimal structure is highly desirable ifnot absolutely necessary. In principle, good contact can be made betweengold plated members with very low contact forces; but, with theexpectation to maintain the contact over many years with no specialcleaning, higher forces are certainly desirable if not an absolutepractical requirement. Optionally, the geometries of the contactingplunger tips may be made more pointed or changed in other ways. Morepointed tips will pierce through obstructions more effectively but willcause more damage to mating contacts. A discussion of other portions andfeatures of the assembly follows.

A fragmentary view of an alternate flanged sleeve 550 which may be usedin place of flanged sleeve 527 is shown in FIG. 5B. To use flangedsleeve 550, a larger hole is drilled in the sash 545, which is shown infragmentary view. An added ledge 546 in flanged sleeve 550 registers thesleeve in the larger hole and provides clearance space 544 between anouter surface 547 of sleeve 550 and the hole in sash 545. This allowsclearance for sleeve 550 to tip slightly so that plunger 530 may beinserted through the cross hole. With this arrangement, hole 529 andenlarged cross hole 531 in the window sash do not need to intersectexactly.

It is necessary to make convenient, reliable contact to both opening andnon-opening variable transmission windows. FIGS. 5C-5E are directedparticularly to non-opening windows with an optional but preferredhollow metal frame. Note that many features of the assembly depicted inFIGS. 5C-5E including the hollow metal frame may be applied to openingwindow assemblies as well and such applications are within the scope ofthis invention. Also, many of the features applied in illustrativeembodiments for opening windows also apply for non-opening windowassemblies as well and such applications are also within the scope ofthis invention. Contact assembly 502 c shown in cross-sectional view isvery similar to the assembly described in detail in FIG. 5A and otherfeatures of FIGS. 5C-5E are similar to corresponding features for thecasement window described in FIG. 6. Details of construction common toand described in either of these related descriptions will not berepeated here. Probe 526 c has been elongated to accommodate the addeddepth of the frame 543 c. Note that insulating sleeves 527 c and 538 celectrically isolate the contact assembly 502 c from the hollow metalframe 543 c in which it is mounted. Contact probe sub-assembly 598 cpasses through hole 599 c in plastic sleeve 527 c and is restrained bysleeve 527 c from being pushed out of place by pressure from probesub-assembly 579 c. Retaining flange 552 c of sleeve 527 c is recessedin a counter bored hole in face 582 c of frame 543 c so that the faceplate 597 e (FIG. 5E) can be mounted directly on the surface of face 582c of the frame. The retaining force is generated between sub-assembly598 c as it bears on the hole 599 c and the flange 522 c as it bearsagainst the ledge in the counter bored hole in the face 582 c of frame543 c. Probe 526 c may have a contact point 585 c which in operationengages connecting pad 587 d (FIG. 5D). The probe tips 585 c and 586 care shown in their normal operating positions when depressed againstcontact pads 587 d and 588 d, respectively, with module 578 d-e mountedin its installed position on the face 582 c of frame 543 c. In the freeposition, the springs of the respective probe sub-assemblies force theprobes to slide out so that they protrude from the face of 582 c of theframe 543 c. Holes 583 c are preferably threaded holes provided toattach module 578 d-e (FIGS. 5D and 5E). Index notch 551 c is providedto indicate proper orientation of sleeve 527 c to accommodate insertionof probe sub-assembly 598 c during the assembly process. The contactassembly 584 c is similar to the assembly 579 c just described.

FIG. 5D depicts the back of the control module which contains thecircuit disclosed in FIGS. 3A-3B. Lead wire 160 d corresponds toterminal 1 and lead wire 161 d corresponds to terminal 2, contact pad587 d corresponds to terminal 43 and contact pad 588 d corresponds toterminal 45 of FIG. 3B. 589d is preferably a portion of a relativelythin, flexible, printed circuit board containing pad 587 d exposed andpreferably gold plated on its front surface as shown in FIG. 5D. Pad 587d is insulated from the back of face plate 597 d and the printed circuitboard 589 d containing pad 587 d is preferably bonded to 597 d. 590 d isthe connecting strip, preferably insulated on both sides, which connectsthe contact pad 587 d with its associated circuit. Pad 588 d issimilarly constructed.

Connecting wires corresponding to signal paths 1004 and 1005 of FIG. 1(not depicted in FIGS. 5C-5E) are normally fished from the wall, througha hole into the frame 543 c at a place not visible in the room andpulled out of opening 581 c and attached to leads 160 d and 161 d.Optionally, the leads 160 d and 161 d may be replaced by a screw type orother type of connector. After connection of the wires, the unit 578 dis turned 180 degrees from the position shown in FIG. 5D to the positionshown in FIG. 5E. The wires are tucked back into the hole 581 c and thebody 591 d of the module is inserted in hole 581 c. Screws are theninserted in countersunk holes 596 e and tightened into threaded holes583 c to secure the module in its operating position. The contactsub-assembly 579 c maintains pressure between pad 587 d and the wall ofprobe sub-assembly 598 c to complete one of the conducting paths to thevariable transmission window which corresponds to element 44 of FIG. 3A.A similar probe sub-assembly in contact assembly 584 c completes theother connecting path to the variable transmission window element. 593 eis an optional display as indicated in 47 a-b of FIG. 1; 594 e is anoptional keypad as indicated in 46 a-b of FIG. 1; and 595 e is anoptional receiver and/or transmitter for a remote interface as indicatedin 51 a-b of FIG. 1.

The module is easy to connect to the variable transmission window, maynormally be placed where it is a convenient control interface to theuser, is accessible for repair or upgrade, and may be neat inappearance.

FIG. 6 depicts an application of two of the contact assemblies depictedin FIG. 5A and of the circuit of FIG. 3A for a hinged or casementwindow. A module 163 is provided on a fixed window frame for housing thecircuit of FIG. 3A. In FIG. 6, lead wire 160 corresponds to terminal 1,lead wire 161 to terminal 2, terminal contact pad 165 to terminal 43,and terminal contact pad 168 to terminal 45. Portion 172 of the verticalportion of window sash 169 includes a contact assembly 164 like thatshown in FIG. 5A and additionally, a second similar contact assembly167, a magnet 173, and the catch for the window latch 166. A variabletransmission window assembly 170 is mounted in sash 169 that containsvariable transmission element 171. The sectioned contact assembly 164contacts a pad 165 when the window is closed. Pad 165 is coupled to thecircuit in module 163. The second identical contact assembly 167contacts a pad 168 when the window is closed and connects to the otherterminal of variable transmission window element 171. Pad 168 is coupledto the circuit in module 163. Element 166 is the catch for the windowlatch assembly and is attached to window sash 169. The mating latchwhich attaches to the frame in which the window sash 169 is hinged isnot shown.

Module 163 is small and is shown in a preferred position where it may berecessed in the fixed frame in which sash 169 is hinged and hidden fromview by being covered by the window latch assembly. In this position, itis out of sight but reasonably accessible for repair. As discussed abovewith respect to FIG. 3A, module 163 optionally contains a magneticallyactuated reed switch that is closed when the window is closed bybringing the reed switch into close proximity with magnet 173 which isembedded in the window sash 169. Other magnetic sensors may optionallybe used in place of the reed switch.

FIG. 7 shows a cross section of a sash 180 of a sliding window or door.This includes double hung windows and windows or doors which slide in ahorizontal direction. In FIG. 7, member 182 is the portion of the frameagainst which the window closes and member 181 is another portion of theframe. There are many similarities to the application of FIG. 6, sofewer details are given. Probe assembly 187 is similar to probe assembly125 of FIG. 5 but with its length adjusted to suit the application.Probe assembly 187 fits in an insulating plastic sleeve 196, which hasan external flange 188 at its upper end to retain it in sash 180 and asection of reduced internal diameter 186 to retain probe assembly 187.Probe assembly 187 includes a probe 184 that is sized to slide freely sothat it telescopes to exert force between a ball 189 and a pad 190 onthe one end and between probe 184 and a pad 183 on the other. Theconstruction shown in FIG. 7 further includes a module 185 in which thecircuit of FIG. 3A may be housed. Module 185 is recessed in the windowframe member 182 and except for a difference in the placement of the twocontact pads of which pad 183 is one, module 185 is very similar tomodule 163 of FIG. 6. A pair of wires 191 and 192 are provided forelectrical connection to the two wire bus and the first pad 183 and thesecond pad (not visible in the cross section) are for connection to avariable transmission window element in window assembly 195. A magnet,not shown, may be embedded in the window sash and actuate an optionalmagnetic sensor in module 185 when window sash 180 is closed.

The embodiments depicted in FIGS. 6 and 7 have the advantage ofrequiring no flexible wires attached between the moving window sash andthe fixed frame but have the disadvantage of losing connection when thewindow sash is open. The embodiment shown in FIGS. 8A and 8B is intendedto maintain the ease of assembly for the installer or manufacturer andto provide continuous connection regardless of whether the window isopen or closed. The window assembly shown in FIGS. 8A and 8B includes aflat, flexible, two conductor cable 246 having a sharp fold with astrain relief at 253. Cable 246 attaches to a small circuit board 243,which is fastened to the hinged side edge of window sash 247. The otherend of cable 246 attaches to circuit module 248 which is recessed in thewindow frame in the area which adjoins the hinged side of window sash247 when the window is closed. The fold in cable 246 opens and extendsrather like a single fold in an accordion bellows when the window isopened and stays neatly in the hinge area. Circuit board 243 has twogold plated pads 242 and 244 on its under side, each of which isconnected, respectively, to one of the cable conductors serving aspermanent contact pads for contact probe assemblies, which are similarto these described in FIG. 7. One of the two probe assemblies havingprobe 241 which contacts pad 242 is shown in section 255.

An embodiment for a double hung window may replace the cords in theconventional block and tackle style lift assemblies with conductorswhich are flexible enough to take repeated flexing around the smalldiameter pulleys in the lift mechanism. If cable with straightconductors of small enough diameter is not practical for a given windowconstruction, options are to use a sandwich with a ribbon of very thinconductive, preferably copper, strip to replace the cord or to use acable where the conductor is wrapped in a helix around the cord havingthe required tensile strength. This configuration has the disadvantagethat the two connections would normally need to be made on oppositesides of the window, one through each of the adapted lift mechanisms.Four pulleys are common in standard lift mechanisms so one end of thecord attaches to the window and the other end to the double pulley whichis attached to the spring. It is preferred to use an odd number ofpulleys, one or three for example, and attach one end of the conductingcord to the window sash and the other to the stationary window framewhere electrical connection could more conveniently be made from it tothe module. A better alternative is to user a single, longer spring witha material of adequate conductivity without the block and tackle pulleysand to make connection to the module at the stationary end of the springand to the window sash at the moving end of the spring. The spring maybe of beryllium copper or preferably of a lower cost alloy that hasreasonable spring properties. A wire with a copper core and a claddingof a stronger more creep resistant material would be ideal.

In an alternate construction shown in exploded view in FIG. 9, a contactleaf spring member 204 is provided having an extended tab 209, which isbonded to an insulating separator 210. A second contact leaf springmember 201 having a mirror image of member 204 is also provided and hasan extended conductive tab 211, which is bonded to the opposing side ofinsulating separator 210. The sandwhiched tab assembly passes through ahole in the window sash to engage and make contact with a receptaclesuch as the shown in FIG. 10 when the window is closed or to makepermanent contact in a non-opening window assembly. Contact 204 sitswith dimpled contact area 207 toward the inner side of a recess in thewindow sash in which the window is glazed and a connector pad 203 ispart of the window assembly similar pad 139 of FIG. 5A but nearly flushwith the edge of the glass panes. Surface 208 of contact 204 bearsagainst the outer side of the recess in which the window is glazed andcantilevered blade 206 is folded back in a radiused bend at 205. Theconfiguration should be such that the surface of blade 206 forms asmooth ramped surface that will not snag the window as it is placed inthe sash in preparation for glazing. Contact member 201 makes connectionwith another terminal pad 202 which is similar in design to pad 203.

The assembly of FIG. 10 depicts a receptacle 229 mated with afragmentary portion of a plug. The plug consists of mating conductors221 and 223, which may be the ends of the sandwiched tabs on thecontacts shown in FIG. 9, and an insulator 222, which may be the end ofinsulating strip 210 also shown in FIG. 9. These components form theplug which is shown mated with the receptacle in FIG. 10. The receptacleincludes an insulating body 227 that is preferably round in outerprofile with a smaller diameter section secured into the window sill anda larger diameter portion extending into a larger diameter hole in thewindow sash. The round profile matches more naturally with holes whichcan be readily put in window structural members to secure the receptaclein the stationary window frame and to allow clearance for the receptacleand plug in the window sash. The “V” shaped section 220 guides the pluginto place when the window is closed. The slot and “V” shaped guideshould be open at the sides so that the plug assembly can preferably bewider than the receptacle assembly. In any event, greater lateralmisalignment can be provided for if the width of the plug does not haveto fit within the diameter of the receptacle. The hole in the sashshould have generous clearance so that for normal window tolerances, thereceptacle will not jam against the sash as the window is closed. Tabs224 allow resilient contact blades 226 and 230 to be pre-loaded andmaintained without shorting when the window is opened and the plugassembly withdrawn. Leads of contact blades 226 and 230 are attached totabs 228 and 231, respectively.

The above description is considered that of the preferred embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove are merely for illustrative purposes and are intended to beincluded within, but not intended to limit the scope of the invention,which is defined by the following claims as interpreted according to theprinciples of patent law, including the doctrine of equivalents.

The invention claimed is:
 1. An electrical control system forcontrolling the transmittance of at least one variable transmissionwindow having a variable transmittance medium and first and secondelectrodes electrically coupled to one another through the variabletransmittance medium, the variable transmittance medium having atransmittance that varies in response to electrical energy appliedthereto via the first and second electrodes, said control systemcomprising: a control circuit coupled to the first and second electrodesof the at least one variable transmission window for selectively varyingthe electrical energy applied across the electrodes to thereby vary thetransmittance of the variable transmission window; a sensing circuit forsensing an abnormal electrical load condition across the firstelectrode, the variable transmittance medium, and the second electrodeof the variable transmission window; and a security system interfacecoupled to receive an indication from said sensing circuit that anabnormal electrical load condition exists in the variable transmissionwindow.
 2. The electrical control system of claim 1, wherein saidabnormal electrical load condition is a near short or near open circuit.3. The electrical control system of claim 1, wherein said controlcircuit comprises a window control circuit coupled to a master controlcircuit, said window control circuit controls the transmittance of thevariable transmission window in response to control signals receivedfrom the master control circuit.
 4. The electrical control system ofclaim 3, wherein said window control circuit includes a memory device inwhich an address is stored that uniquely identifies said window controlcircuit to the master control circuit.
 5. The electrical control systemof claim 1 and further including a device coupled to said controlcircuit for supplying information to said control circuit.
 6. Theelectrical control system of claim 5, wherein said device includes atemperature sensor.
 7. The electrical control system of claim 5, whereinsaid device includes a light sensor.
 8. The electrical control system ofclaim 1, wherein the variable transmission window is an electrochromicwindow.
 9. The electrical control system of claim 1, wherein at leastone of said control circuit includes a micro controller and a switchingregulator circuit for supplying power to the variable transmissionwindow, said switching regulator circuit is coupled to said microcontroller and is responsive to signals received from said microcontroller to selectively vary the power supplied to the variabletransmission window.
 10. The electrical control system of claim 9 andfurther including an over-voltage protection circuit coupled to anoutput of said switching regulator circuit for protecting the variabletransmission window from over-voltage conditions.
 11. The electricalcontrol system of claim 9 and further including a current limitingcircuit coupled to said switching regulator circuit for preventingexcessive current from flowing through the variable transmission window.12. The electrical control system of claim 9 and further including atemperature sensor coupled to said micro controller for supplying atemperature signal indicative of an internal air temperature proximatethe variable transmission window, wherein said micro controller respondsto said temperature signal by controlling said switching regulatorcircuit to vary the transmission of the variable transmission window.13. The electrical control system of claim 9 and further including alight sensor coupled to said micro controller for supplying a lightlevel signal indicative of a light level on the inside of the variabletransmission window, wherein said micro controller responds to saidlight signal by controlling said switching regulator circuit to vary thetransmission of the variable transmission window.
 14. The electricalcontrol system of claim 9 and further including an input device coupledto said micro controller for receiving input from a user and supplyingthe input to said micro controller.
 15. The electrical control system ofclaim 9 and further including a display coupled to said micro controllerfor displaying status information to a user.
 16. The electrical controlsystem of claim 9 and further including a receiver for receiving acommand from a remote control device via a wireless communication link,said receiver is coupled to said micro controller to supply a controlsignal representing the received command, wherein said micro controllerresponds to the receipt of a control signal by causing said switchingregulator circuit to vary the transmittance of the variable transmissionwindow.
 17. The electrical control system of claim 1, wherein saidsensing circuit is electrically coupled to the first electrode and thesecond electrode of the variable transmission window.
 18. A buildingcomprising: a plurality of variable transmission windows, each includinga variable transmission medium and a pair of electrodes to which signalsmay be applied to said variable transmission medium to vary thetransmission of said variable transmission medium; a master controlcircuit for supplying control signals representing transmittance levelsfor said variable transmission windows; a plurality of window controlcircuits coupled to said master control circuit, each window controlcircuit coupled to the pair of electrodes of at least one of saidvariable transmission windows for controlling the transmittance of atleast one of said variable transmission windows in response to controlsignals received from said master control circuit; a sensing circuit forsensing an abnormal electrical load condition across the pair ofelectrodes and the variable transmission medium of at least one of thevariable transmission windows; and a security system interface coupledto receive an indication from said sensing circuit that an abnormalelectrical load condition exists in one of the variable transmissionwindows.
 19. The building of claim 18, wherein said master control unitpolls each of the window control units to signal changes which indicatea probable breach of security.
 20. The building of claim 18, whereinsaid window control units detect window closure status and report windowopening to the security system interface.
 21. The building of claim 18,wherein said window control circuits each include a memory device inwhich an address is stored that uniquely identifies the window controlcircuit to said master control circuit.
 22. The building of claim 18,wherein said master control circuit and said window control circuits arecoupled via a two-way data link.
 23. The building of claim 18, whereinsaid master control circuit and said window control circuits are coupledvia a low voltage power line pair.
 24. The building of claim 23, whereinsaid master control circuit supplies power to said window controlcircuits over said low voltage power line pair.
 25. The building ofclaim 24, wherein said master control circuit and said window controlcircuits perform bi-directional communication over said low voltagepower line pair.
 26. The building of claim 18, wherein said variabletransmission windows are electrochromic windows.
 27. The building ofclaim 18, wherein said sensing circuit is electrically coupled to bothof the pair of electrodes of at least one of the variable transmissionwindows.
 28. A method of determining whether a security breach hasoccurred through the breakage or opening of a variable transmissionwindow, the variable transmission window providing a current path whenclosed, where the current path passes through a pair of electrodes and avariable transmission medium of the variable transmission window andwhere the current path is used to selectively vary the transmission ofthe variable transmission window, the method comprising the steps of:sensing whether there is an abnormal electrical load condition in thecurrent path through the variable transmission window; and determiningthat there has been a security breach through the variable transmissionwindow when an abnormal electrical load condition is sensed.
 29. Themethod of claim 28, wherein the abnormal electrical load condition is anear short or near open circuit.
 30. The method of claim 28, wherein theabnormal electrical load condition includes an open circuit that occurswhen a window is open.